Multi-break resistance shunted circuit breaker with a vacuum switch as the final interrupter



Aug. 15, 1961 G E. HEBERLEIN ETAL 2,996,592

MULTI-BREAK RESISTANCE SHUNTED CIRCUIT BREAKER WITH A VACUUM SWITCH ASTHE FINAL INTERRUPTER Filed Dec. 30. 1958 3 Sheets-Sheet l INVENTORS 605774145 6. #68594 5711/ Aug. 15, 1961 G. E. HEBERLEIN ET AL 2,996,592

MULTI-BREAK RESISTANCE SHUNTED CIRCUIT BREAKER WITH A VACUUM SWITCH ASTHE FINAL INTERRUPTER Filed Dec. 30, 1958 3 Sheets-Sheet 2 Z-T'E- 51 L-I5-. 5

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Aug. 15, 1961 G. E MULTI-BREIAK RESIS A VACU Filed Dec. 30. 1958HEBERLEIN ET AL TANCE SHUNTED CIRCUIT BREAKER WITH UM SWITCH AS THEFINAL INTERRUPTER 3 Sheets-Sheet 3 III United States Patent MMULTI-BREAK RESISTANCE SHUNTED CIRCUIT BREAK'ER WITH A VACUUM SWITCH ASTHE FINAL INIERRUPTER Gustave E. Heberlein, Wayne, and William A.Carter,

Chester, Pa., assignors to I-T-E Circuit 'Breaker Company, Philadelphia,Pa., a corporation of Pennsylvania Filed Dec. 30, 1958, Ser. No. 783,894Claims. (Cl. 200-145) The instant invention relates to magnetic aircircuit breakers and more particularly to a circuit breaker of this typewherein a resistor is inserted in shunt with the arc, in order to limitthe arc current and to improve the power factor thereof, and including avacuum switch as the final interrupter means.

As explained in the copending application Serial No. 731,769, filedApril 29, 1958 entitled Multiple Break Air Magnetic Breaker, with J. D.Wood as the inventor, and assigned to the assignee of the instantinvention, a resistor may be inserted in series with each portion,except the initial portion, of the are drawn in a multi-break magneticair circuit breaker. The resistor serves to reduce the value of the arccurrent and also improve the power factor of the circuit prior to finalinterruption thereby preventing the occurrence of transient voltagesurges which could cause restriking of the arc. Since each succeedingportion of the arc is of a reduced current magnitude, means are providedwhereby the intensity of themagnetic field, covering the portion of theinterrupter whose function it is to interrupt the arc of reducedcurrent, must be increased as the arc current decreases.

The circuit breaker must be constructed to quickly and efficientlyinterrupt currents limited by shunt resistance during periods of faultas well as highly inductive currents of low magnitude which might behandled while switching an unloaded transformer. Previously,magnetically excited blow-out coils of many turns were suggested toclear these currents. Thus, the design of the interrupter wascomplicated by the special construction of the blow-out coils, and evenwith this special construction low values of current continued topresent an appreciable problem.

The device of the instant invention provides a means whereby theresistive fault currents as well as highly inductive currents of lowmagnitude are quickly and efliciently interrupted. This is achieved byutilizing a high vacuum switch connected in the circuit to act as afinal interrupter. The vacuum switch is connected in series with aresistor so that the switch is then required to handle currents whichrange from the maximum value of current which the resistor will pass tovery low values such as transformer magnetizing current. The circuitbreaker of the instant invention is constructed in a manner such thatthe vacuum switch is automatically isolated from the circuit through thenormal operation of the circuit breaker. This serves to improve thebasic impulse level of the circuit breaker and insures complete circuitisolation. Isolating the vacuum switch is highly desirable since theswitch is enclosed within a glass envelope 'which is susceptible tobreakage. Further, the impulse level of the switch drops as a result ofcontaminants caused by repeated switch operation.

Accordingly, a primary object of the instant invention is to provide anovel multi-break resistance air magnetic shunt circuit breakerutilizing a high vacuum switch as the final interrupter.

Another object is to provide a multi-break magnetic air circuit breakerincluding a vacuum switch as well as an isolating switch which are bothoperated from the 2,996,592 Patented Aug. 15, 1961 main contact bridgeof the circuit breaker to efiiciently interrupt the circuit and toautomatically isolate the vacuum switch and the remaining portions ofthe circuit breaker from the circuit.

These as well as other objects of the instant invention shall becomereadily apparent after reading the following description of theaccompanying drawings in which:

FIGURE 1 is a side elevation of the circuit breaker in the closedposition.

FIGURE 2 is a side elevation illustrating the contact structure ofFIGURE 1 with the main contacts in the open position and the othercontacts in the closed position.

FIGURE 3 is a side elevation showing the contact structure at theposition wherein the main contacts and the vacuum switch are both openedwhile the isolation switch is still closed.

FIGURE 4 is a side elevation at the position wherein all of the contactsare opened.

FIGURE 5 is a schematic representation of the circuit breaker of FIGURES1-4.

FIGURE 6 is a schematic illustrating a circuit breaker constructed inaccordance with the instant invention in which the arc chute is dividedinto two sections with an individual current limiting resistor inparallel with each section.

Now referring more particularly to FIGURE 5, circuit breaker 20comprises a lower current stud 21 and an upper current stud 22 suitablyinsulated from each other to which external circuit connections aremade. Stationary arcing contact 23 and main contact 25 are mounted tothe end of upper stud 22. Movable main contact 26 and movable arcingcontact 24, which are engageable with stationary contacts 25, 23respectively, are mounted to one end of bridge 27 which is pivoted atits other end 28 to lower .stud 21.

Arc chute 29 is positioned above cooperating contacts 23, 24 and 25, 26to receive an electric current are drawn between. these contacts uponparting thereof. Blowout coil 30, connected between upper stud 22 andrear arc runner 31, is operatively positioned to force the arc into arcchute 29 where the arc will be elongated and cooled by the spaced arcplates 29 which force the arc to travel a tortuous path from rear runner31 to front are runner 32. An insulating means 33 usually in the form ofa jump gap, is interposed between movable arcing contact 24 and rearrunner 31 to extinguish. the are drawn between arcing contacts 23, 24 bydiverting the arc current through blowout coil 30. The structurehereinbefore described may take any one of many forms well known to thecircuit breaker art.

Arc chute'29 is paralleled by a series circuit, comprising a resistor 34and a normally closed vacuum switch 35 connected between the front andrear arc runners 32 and 31 respectively. Vacuum switch 35 is of the typedescribed in the US. Patent 2,740,867 to I. E. Jennings and comprises apair of axially aligned contact studs 36, 37. Contact stud 37 is axiallymovable by means of an operative insulating connection, indicated by thedotted line 38 extending between switch 35 and bridge 27 as willhereinafter be fully explained.

When the arc current is transferred to blowout coil 30 the arc is forcedinto arc chute 29 and extends between rear runner 31 and movable arcingcontact 24. As the arc moves upward in chute 29 it transfers frommovable arcing contact 24 to front runner 32. With continued upwardmovement of the arc the series circuit 34, 35 provides the lowestresistance path between the arc runners 31, 32 so that the arc currentis shunted to series circuit 34, 35 and the arc is interrupted.

At this time the current is limited by the value of resistor 34 which ispreferably, though not necessarily, of a value which will limit thecurrent to a value within the continuous current rating of vacuum switch35. Continued clockwise movement of bridge 27 about pivot 28 then causesthe operative connection 38 to bring about the opening of vacuum switch35 thereby interrupting the current flowing through resistor 34 which isthe current of the external circuit.

Continued clockwise movement of bridge 27 causes movable isolatingcontact 39 to separate from stationary isolating contact 40 which ismounted to the lower end of front are runner 32. Movable isolatingcontact 39 is mounted to one end of conducting contact arm 41 which ispivotally mounted at 42 to bridge 27. The separation of isolatingcontacts 39, 40 effectively isolates the remaining portions of circuitbreaker 20 from the external circuit. Thus, there is a sequentialoperation of cooperating contacts 23, 24, vacuum switch 35 and isolatingcontacts 39, 40 which is brought about by the mechanical connectionsbetween bridge 27, contact arm 41 and insulating connection 38 whichwill be fully explained in the following description.

=Now referring more particularly to FIGURES 1-4, the structure foundtherein will be tied into the schematic of FIGURE wherever possible bythe utilization of common reference numbers between all of thesefigures. Movable contacts 24, 26 are secured to contact member 43 whichis pivotally mounted at 44 to bridge 27. A biasing means (not shown)urges cont-act member 43 counterclockwise about pivot 44 so that upon aclockwise movement of bridge 27 from the position of FIGURE 1 to theposition of FIGURE 2, main contacts 25, 26 will separate before arcingcontacts 23, 24. Similarly, upon movement of bridge 27 in acounterclockwise direction, arcing contacts 23, 24 will be brought intoengagement before main contacts 25, 26.

One end of insulating connection 38 is pivotally connected at 45 tobridge 27. An elongated slot 46 is formed in connection 38 near theother end thereof. Pin 47 positioned at the end of one arm of crank 48is disposed within slot 46. Crank 48 is pivotally mounted to stationarypivot 49 and the other end of crank 48 is secured to one end of tensionspring 50 whose other end is secured to stationary point 51 therebybiasing crank 48 clockwise about pivot 49. Thus, crank tip 52 is biasedtoward engagement with extension 53 which is secured to the free end ofL-shaped yieldable member 54', secured at its other end to front arerunner 32 by means of fasteners 55, 56.

Vacuum switch 35 is mounted at its lower end to conducting bracket 57 bymeans of fasteners 58 while bracket 57 is secured to front are runner 32by means of fasteners 55, '56 and 59, 60. The upper end of vacuum switch35 is secured to conducting bracket 61 by means of fasteners 62, 63while bracket 61 is secured by fasteners 64 to the insulating shell 65of arc chute 29. A U-shaped member 66 having inwardly turned ends issecured to bracket 57 below vacuum switch 35 by fastening means 58.

Movable contact stud 37 extends through bellows 67 to a point outside ofevacuated envelope 68 and is operatively engaged by lock nuts 69, 70.Threaded stud 71, extending upwardly from extension 53, passes throughopening 72 in the bottom of U-shaped member 66 and is received by locknut 70. Coil spring 54 is interposed between lock nut 69 and a sleeve69' projecting downward from bracket 57 with the lower end of stud 37extending therethrough. Spring 50 biases crank tip 52 into engagementwith extension 53 with a force sufficient to overcome the force ofspring 54 thereby enabling contact stud 37 to engage contact stud 36.

I When bridge 27 is moved from the position of FIG- URE 1 to that ofFIGURE 2, elongated slot 46 moves relative to pin 47 so as not to causerotation of crank 48. However, continued clockwise movement of bridge 27from the position of FIGURE 2 to that of FIGURE 3 causes the bottomsurface 46a of slot 46 to engage pin 47 thereby rotating crank 48counterclockwise about pivot 49. This permits spring 54 to move threadedstud 71 downward carrying contact stud 37 with it thereby opening vacuumswitch 35. The separation between contact studs 36, 37 is limited by theengagement of lock nut 70 with U-shaped member 66.

Continued clockwise movement of bridge 27 between the positions ofFIGURES 3 and 4 will bring about additional counterclockwise movement ofcrank 48. However, the engagement between lock nut 70 and U-shapedmember 66 prevents further separation of movable contact stud 37 fromstationary contact 36.

Extension 73 of contact arm 41 is connected by means of pin 74 to rodassembly 75 near one end thereof. The other end of rod assembly 75 isconnected by means of pin 76 to an extending portion 77 of bridge 27.Rod assembly 75 comprises a stud member 78 which is in threadedengagement with elongated member 79. An elongated slot 80 in member 79is provided to receive pin 76. Compression spring 81 bears against pin76 and flange 82 of stud member 78 thereby biasing contact arm 41counterclockwise about pivot 42.

Movement of bridge 27 between its positions of FIG- URES 2 and 3 willpermit an expansion of spring 81 causing a counterclockwise rotation ofcontact arm 41 about pivot 42 which maintains movable contact 39 inengagement with stationary isolating contact 40. As bridge 27 is pivotedclockwise about pivot 28 from position 3 to position 4 the bottomsurface 80a of elongated slot 80 engages pin 76 thereby preventingfurther counterclockwise movement of contact arm 41. This enablesisolating contacts 39, 40 to be disengaged. The setting of the distancesbetween pins 74 and 76 determines the point in the opening stroke ofbridge 27 when isolated contacts 39, 40 will separate.

It is to be understood that bridge 27 may be moved by any suitablecircuit operating mechanism acting through link 83.

In FIGURE 6 there is illustrated a modification of the circuit breakerhereinbefore described. This modification comprises a connection of theseries circuit 34, 35 between the front are runner 32 and a mid-runner84 which is positioned between the front 32 and rear 33 are runners. Asecond current limiting resistor 85 is connected between mid-runner 84and rear are runner 31.

With this latter construction the separation of arcing contacts 23, 24will first cause an arc to be drawn in the near portion of arc chute 29between mid-runner 84 and rear arc runner 31. As this are is elongatedand deionized in the rear portion of chute 29 the arc current will betransferred to resistor 85 and the current through resistor 85 will'appear as an arc in the front portion of chute 29 between mid-runner 84and front runner 32.

When this are has been driven sufficiently toward the top of chute 29,the current thereof will transfer to the series circuit of resistor 34and vacuum switch 35. This current will be interrupted by the opening ofvacuum switch 35 and thereafter contacts 39, 40 will separate to isolatethe other portions of the circuit breaker.

Thus, we have provided a novel circuit breaker utilizing a multi-breakprinciple having resistance means to limit the arc current and improvethe power factor there of prior to final interruption by a vacuumswitch.

Although we have here described preferred embodiment of our novelinvention, many variations and modifications will now be apparent tothose skilled in the art, and we therefore prefer to be limited, not bythe specific disclosure herein, but only by the appending claims.

We claim:

1. A circuit breaker comprising a bridge movable from a first to asecond position and from a second to a third position, a pair ofcooperating contacts one of which is stationary and the other of whichis carried by said bridge, a vacuum switch and an insulating connectionextending from said bridge into operative engagement with said switch,an arc extinguishing means including an arc chute and a magnetic meansoperatively positioned to force an electric current are formed by theparting of said contacts into said are chute; said are chute comprisinga first runner, a second runner, and a plurality of spaced arc platesstacked between said runners; a series circuit, comprising a resistorand said switch, connected across at least a portion of said chute; saidcontacts being engaged and said switch being closed when said bridge isin said first position; said contacts being disengaged and said switchbeing closed when said bridge is in said second position; said contactsbeing disengaged and said switch being open when said bridge is in saidthird position.

2. A circuit breaker comprising a bridge movable from a first to asecond position and from a second to a third position, a first pair ofcooperating contacts one of which is stationary and the other of whichis carried by said bridge, a vacuum switch and an insulating connectionextending from said bridge into operative engagement with said switch,an arc extinguishing means including an arc chute and a magnetic meansoperatively positioned to force an electric current are formed by theparting of said contacts into said arc chute; said arc chute comprisinga first runner, a second runner, and a plurality of spaced arc platesstacked between said runners; said magnetic means being connected tosaid first runner; a series circuit, comprising a rwistor and saidswitch, connected across at least a portion of said chute; said contactsbeing engaged and said switch being closed when said bridge is in saidfirst position; said contacts being disengaged and said switch beingclosed when said bridge is in said second position; said contacts beingdisengaged and said switch being open when said bridge is in said thirdposition; an arm mounted to said bridge; a second pair of cooperatingcontacts one of which is mounted to said second runner and the other ofwhich is mounted to said arm; said bridge also being movable from saidthird position to a fourth position; said second pair of contacts beingclosed while said bridge is in said first, said second, and said thirdpositions; said second pair of contacts being opened by the movement ofsaid bridge from said third position to said fourth position.

3. A circuit breaker comprising a bridge movable from a first to asecond position and from a second to a third position, a first pair ofcooperating contacts one of which is stationary and the other of whichis carried by said bridge, a vacuum switch and an insulating connectionextending from said bridge into operative engagement with said switch,an arc extinguishing means including an arc chute and a magnetic meansoperatively positioned to force an electric current arc formed by theparting of said contacts into said are chute; said are chute comprisinga first runner, a second runner, and a plurality of spaced arc platesstacked between said runners; said magnetic means being connected tosaid first runner; a series circuit, comprising a resistor and saidswitch, connected across a portion of said chute; said contacts beingengaged and said switch being closed when said bridge is in said firstposition; said contacts being disengaged and said switch being closedwhen said bridge is in said second position; said contacts beingdisengaged and said switch being open when said bridge is in said thirdposition; said are chute portion extending to said second runner; and aresistance means shunting the remaining portion of said are chute.

4. A circuit breaker comprising a bridge movable from a first to asecond position and from a second to a third position, a first pair ofcooperating contacts one of which is stationary and the other of whichis carried by said bridge, a vacuum switch and an insulating connectionextending from said bridge into operative engagement with said switch,an arc extinguishing means including an arc chute and a magnetic meansoperatively positioned to force an electric current arc formed by theparting of said contacts into said arc chute; said arc chute comprisinga first runner, a second runner, and a plurality of spaced arc platesstacked between said runners; said magnetic means being connected tosaid first runner; a series circuit, comprising a resistor and saidswitch, connected across a portion of said chute; said contacts beingengaged and said switch being closed when said bridge is in said firstposition; said contacts being disengaged and said switch being closedwhen said bridge is in said second position; said contacts beingdisengaged and said switch being open when said bridge is in said thirdposition; said are chute portion extending to said second runner; and aresistance means shunting the remaining portion of said arc chute; anarm mounted to said bridge; a second pair of cooperating contacts one ofwhich is mounted to said second runner and the other of which is mountedto said arm; said bridge also being movable from said third position toa fourth position; said second pair of contacts being closed While saidbridge is in said first, said second, and said third postions; saidsecond pair of contacts being opened by the movement of said bridge fromsaid third position to said fourth position.

5. In a magnetic circuit breaker; said magnetic circuit breakercomprising a stationary contact, a movable contact movable between anengaged and disengaged posi- ,tion with respect to said stationarycontact, a blowout coil, a jump gap, a disconnect switch having firstand second relatively movable contacts and an arc chute; said are chuteextending between a first arc runner and a second arc runner; saidmagnetic circuit breaker having a first and second terminal; said firstterminal being connected to a first end of said blowout coil and saidstationary contact; the opposite end of said blowout coil beingconnected to said first arc runner; said jump gap being interposedbetween said stationary contact and said first arc runner; said secondarc runner being connected to said first contact of said disconnectswitch; said second disconnect contact being connected to said secondterminal of said circuit breaker; a shunt circuit comprising a resistorconnected in series with a vacuum switch; one end of said shunt circuitbeing directly connected to said first arc runner; the opposite end ofsaid shunt circuit being directly connected to said second arc runner;and coordinating means; said coordinating means being connected to saidcircuit breaker movable contact, said disconnect switch, and said vacuumswitch; said coordinating means being operable for causing apredetermined sequential operation whereby said movable contact firstmoves toward its said disengaged position, said vacuum switch thereafteroperates to an open circuit condition, and said disconnect switchthereafter opens.

References Cited in the file of this patent UNITED STATES PATENTS1,783,279 Burham Dec. 2, 1930 2,345,724 Baker et a1. Apr. 4, 19442,480,622 Warnock Aug. 30, 1949 2,748,226 MacNeill et a1. May 29, 19562,815,418 Latour Dec. 3, 1957 FOREIGN PATENTS 344,867 Great Britain Mar.10, 1931 547,270 Germany Mar. 22, 1932 392,898 Great Britain 1933579,464 Germany June 27, 1933

